Allow null numbers and validate them correctly (#182)

* Allow null numbers and validate them correctly

* Revert string number validator. Handle null numbers

* Validate null number

Author: AramAlsabti

src/config/constants/pagination-constants.ts

@@ -0,0 +1,2 @@
+export const DefaultLimit = 100;
+export const DefaultOffset = 0;

src/entities/dto/list-all-applications.dto.ts

@@ -1,15 +1,35 @@
-import { ApiPropertyOptional } from "@nestjs/swagger";
-
+import { DefaultLimit, DefaultOffset } from "@config/constants/pagination-constants";
 import { ListAllEntitiesDto } from "@dto/list-all-entities.dto";
-import { StringToNumber } from "@helpers/string-to-number-validator";
 import { IsSwaggerOptional } from "@helpers/optional-validator";
+import {
+    NullableStringToNumber,
+    StringToNumber,
+} from "@helpers/string-to-number-validator";
+import { ApiProperty, OmitType } from "@nestjs/swagger";
+import { Transform } from "class-transformer";
+import { IsOptional, IsNumber } from "class-validator";
 
-export class ListAllApplicationsDto extends ListAllEntitiesDto {
+export class ListAllApplicationsDto extends OmitType(ListAllEntitiesDto, [
+    "limit",
+    "offset",
+]) {
     @IsSwaggerOptional({ description: "Filter to one organization" })
     @StringToNumber()
     organizationId?: number;
 
     @IsSwaggerOptional({ description: "Filter to one permission" })
     @StringToNumber()
     permissionId?: number;
+
+    @ApiProperty({ type: Number, required: false })
+    @IsOptional()
+    @IsNumber()
+    @Transform(({ value }) => NullableStringToNumber(value))
+    limit? = DefaultLimit;
+
+    @ApiProperty({ type: Number, required: false })
+    @IsOptional()
+    @IsNumber()
+    @Transform(({ value }) => NullableStringToNumber(value))
+    offset? = DefaultOffset;
 }

src/entities/dto/list-all-entities.dto.ts

@@ -1,3 +1,4 @@
+import { DefaultLimit, DefaultOffset } from "@config/constants/pagination-constants";
 import { StringToNumber } from "@helpers/string-to-number-validator";
 import { ApiProperty } from "@nestjs/swagger";
 import { IsOptional, IsString } from "class-validator";
@@ -6,11 +7,11 @@ export class ListAllEntitiesDto {
     @ApiProperty({ type: Number, required: false })
     @IsOptional()
     @StringToNumber()
-    limit? = 100;
+    limit? = DefaultLimit;
     @ApiProperty({ type: Number, required: false })
     @IsOptional()
     @StringToNumber()
-    offset? = 0;
+    offset? = DefaultOffset;
     @ApiProperty({ type: String, required: false })
     @IsOptional()
     @IsString()

src/helpers/string-to-number-validator.ts

@@ -12,3 +12,17 @@ export const StringToNumber = (): PropertyDecorator => {
         IsNumber()(propertyValue, propertyName);
     };
 };
+
+/**
+ * Fixes unexpected behaviour when casting using @Type() decorator. When casting a query parameter using
+ * Type() or Transform() from class-transformer, all parameters with the same decorator are casted.
+ * That's unexpected behaviour.
+ * @param value
+ */
+export const NullableStringToNumber = (value: unknown): number | null => {
+    if (value === null || value === "null") {
+        return null;
+    }
+
+    return Number(value);
+};